Bands by letter: O
- [o3]
- Obdurate Seduction
- Obituary
- Objective Zero
- Obliveon
- Obscene Crisis
- Obscenity
- Obscura
- Obscurant
- The Obsessed
- Obsession
- Obsidian (NL)
- Obsidian (UK)
- Obtained Enslavement
- Obtest
- Obus
- Occult
- The Ocean
- Ocean Machine
- October 31
- October Tide
- Octopus
- Odal
- Odd Logic
- Odes Of Ecstasy
- Odin's Court
- Odious Mortem
- Odium
- Odyssey
- Odyssey (US)
- Ofermod
- Of Infinity
- Ofryskje
- Ohm
- Eddie Ojeda
- The Old Dead Tree
- Old Funeral
- Old Man Gloom
- Old Man's Child
- Old Wainds
- Oligarquia
- Oliver/Dawson Saxon
- Oliver Magnum
- Jarle H. Olsen
- Ol Sonuf
- Olympos Mons
- Omen
- Omission
- Omnium Gatherum (AUS)
- Omnium Gatherum (FIN)
- Ondskapt
- The One
- One Man Army and the Undead Quartet
- One Step Beyond
- One Way Mirror
- Ongo
- Oni
- Onkel Tom Angelripper
- Only Living Witness
- Onslaught
- Onward
- Oomph!
- Opened Paradise
- Open Hell
- Opera IX
- Opera Magna
- Opeth
- Opfer Rasssenhass
- Ophiolatry
- Ophthalamia
- Opposite Earth
- Opprobrium
- Optimum Wound Profile
- Opus Atlantica
- Opus Tide
- Oracle
- Oratory
- Orcustus
- Ordained Genocide
- The Ordher
- Order From Chaos
- Order of Chaos
- Order Of Ennead
- Ordo Templi Aeternae Lucis
- The Organization
- Orgy of Pigs
- Origin
- Ormgård
- Ornaments Of Sin
- Ornias
- Oro
- Orodruin
- Oroku Saki
- Orphanage
- Orphaned Land
- Orthrelm
- Ozzy Osbourne
- O.S.I. (Office of Strategic Influence)
- Osiris
- Otep
- Otyg
- Outworld
- Overcast
- Overflash
- Overkill
- Overlord's Perpetual